Whewww... wow I went and found your stonehall thread and read your intro for it. Glad I brought my climbing gear for it (can of soda and a bag of chips), cause your walls of text put dwarven quantum walls to shame.
I'll also add that Age of Wonders was awesome, and I've on several occasions thought about modding in karaghs for the goblins (my favorite evil race in AoW) teehee. And I did like your idea of a fantasy kitchen sink for each of the races err alliances.
Anyways back on topic. I'd say they are female dominated, the male caste would probably be rarer than the females by quite a bit and maybe a bit smaller than the females. Also I don't know if you could do all female and have them reproduce at all. And besides got to be able to use the beefcake sprite afterall.
The body raws, well I'm not too good with those. Those have always confused me for the most part. Though I guess you could start them out at size 80,000 maybe 90,000, which would put them bigger than humans by a bit though I'd imagine their human halves were fairly close to the same size as a human, most of their increased size is in their tails. Maybe give them snake fangs with a mild venom (nothing major) and the forked tongues. Or if possible some sort of constriction attack, probably not possible though.
I'd imagine they'd just have the upper body stuff. Almost every naga/lamia in any story/game/whatever I've seen has left the snake half unclothed. Though we could invent some clothing/armour for them if you want. Leaving the tails unarmoured/unclothed might be a way to balance their increased size advantage too, though maybe thicken the scale layer a bit.
As for personalities, I'm sort of leaning towards Bleu. A bit lazy, and carefree considering their power. I'll probably think of some more characteristics later, though. It's getting kind of late and the alarm clock rings aweful early in the morning.